The present invention relates to control systems for vehicles. In particular, the present invention relates to a stability control system for an automotive vehicle.
Stability has always been a factor in designing a safer automobile. Stability is necessary to prevent skidding of an automobile or other vehicle in poor traction, during turning, acceleration, and deceleration. Prior art devices have attempted to control several parameters when attempting to improve traction, including controlling speed, acceleration, and torque. Another such way to control stability involves measuring yaw. Yaw is the angular turning around a vertical axis located in the center of the vehicle. In these inventions, a measured yaw is compared to a calculated desired yaw. The difference between the two yaws is a yaw rate error. In prior implementations, this calculation has been used to apply braking, adjust steering, or to adjust torque to counter skidding.
These prior art systems were typically expensive, requiring several separate sensors to control the vehicle. Furthermore, while the prior art systems improved stability, they did not improve launch performance of the vehicle. The launch performance is the ability of the vehicle to obtain and maintain traction during initial acceleration. Therefore, prior implementations did not satisfy the need for an inexpensive, modular stability control system which improved launch capabilities.
The invention provides an improved system to control vehicle stability through the use of yaw rate error and the method for using the system. The system provides improved handling through front-to-rear torque biasing, side-to-side torque biasing, and braking intervention. Furthermore, the application of this system increases mobility, precision, and launch capabilities. Finally, the invention provides a system that improves stability, agility, and precision by utilizing a low cost, modular design.
An embodiment of the invention includes at least one sensor. This sensor detects the yaw rate of the vehicle and translates that yaw rate into a signal. The embodiment also includes a controller that is in electric communication with the sensor and receives the yaw rate from the sensor. The controller compares the measured yaw rate with a calculated, desired yaw rate and creates a yaw torque target signal for achieving the desired yaw rate. This yaw torque target signal is then sent to at least one electric driveline, that adjusts torque in response to the yaw torque target signal.
In another aspect of the invention, an embodiment of a method of controlling vehicle stability is provided. The method measures the yaw rate of a vehicle and converts it into a signal. This signal is sent to a controller which determines the conditions of the vehicle, receives driver input, and determines a desired yaw rate from this information. The controller then compares the desired yaw rate to the measured yaw rate and calculates a yaw torque target signal that is sent to independently controlled electric drivelines. The electric drivelines then apply torque according to the yaw torque target signal.
Other systems, methods, features, and advantages of the invention will become apparent to one skilled in the art upon examination of the following figures and detailed description. All such additional systems, methods, features, and advantages are intended to be included within this description, within the scope of the invention, and protected by the accompanying claims.